I do not want to be an alarmist but please be careful this is not a false widow spider as these are becoming more widespread in this country due to so called global warming,
The female can give a very nasty bite

There are a range of spiders known as false widow spiders which this belongs to ..its commonly known as the biting spider will give a painful nip but not poisonous. Steatoda nobilis becoming more widespread in UK .Common in Mediterranean often imported in to UK so being near a busy port might explain this.

Thanks to all for your answers. I contacted the British Arachnological Society with the pictures and found that it is indeed a false widow but not one that is implicated in biting humans. The name of the spider is Steatoda Bipunctata.